It has been known that some isothiazole derivatives have an activity for control of plant diseases (Patent Literature 1). The compounds described in the literature, however, are compounds in which methyl group is bonded to the 3-position of isothiazole ring, and the literature describes no 3,4-dihalogenoisothiazole derivative represented by the general formula [I] of the present application.    Patent Literature 1: JP-A-2005-82486